Mr White's "Opus", designing a simple balanced DAC

[Nortp]

I swapped the LM317 and LM337 and all is well. I hooked up the balsie and I'm listening to it right now. The balsie really seems to give a lot more gain and maybe a little more solid bass. Russ/Brian great project and thanks for your help and patence.

PJN

[SoapSeller]

I've got my opus running and it sound great. But --
I've got a loud "click" noise when I'm powering the Opus on/off(louder when on), the click is louder on one channel.

I'm using dual mono configuration with the ballsie without any the filter caps. And I've sorted the outputs on the dac boards like kstlfido did.

I'll take some pictures tomorrow, any ideas in the meanwhile?

[Russ White]

Originally posted by SoapSeller
I've got my opus running and it sound great. But --
I've got a loud "click" noise when I'm powering the Opus on/off(louder when on), the click is louder on one channel.

I'm using dual mono configuration with the ballsie without any the filter caps. And I've sorted the outputs on the dac boards like kstlfido did.

I'll take some pictures tomorrow, any ideas in the meanwhile?

A small click is nearly unavoidable unless you decide to rig output relays or some such scheme. They should be completely harmless.

One thing I have noticed in my testing is that if you feed both VA and VD from the same PS (one half of a LCDPS) then the "off" click seems to be less. I believe this is because the VA and VD voltage will decay at (nearly) the same rate. if you allow VD to remain high while VA is going low you can indeed get some nasty noises.

Personally, have only rarely ever gotten a barely perceptible "on" click, mostly the turn on is silent.

I hope that helps.

Cheers!
Russ

[rjbaldwin]

Well after a bit of fiddling I ended up with DAC sans capacitors and with Ballsie sans extra filter capacitors. The Ballsie didn't seem to detract from the music, added some useful gain, at least in single ended mode and added a little 'punch' I thought with my and with my 300B's. It also enabled me to remove the caps from the DAC - which seemed best whilst minimising DC into my TVC. This seemed to give the best results going into my system (see previous post) your mileage may vary.

It really is rather good ;-) Fast, tight bass, clear treble and good clarity. Depth seems good but I wasn't so sure about width, but (big BUT) - my speaker placement is not ideal for this, so you should take this with a pinch of salt. (Also it could be the DAC is accurately reproducing what is on the recording!)

Compared to top flght kit, the DAC perhaps lacks a little air or transparency and a touch of fluidity - at least in my system. This is only very slight and I am talking about a CD/DAC in the £5000 (GBP) bracket, even if it is an old one.

So, yes, computer based replay can get pretty close to high end stuff. Now if I could just capture that extra bit of transparency/fluidity I'd be completely happy.

In any event, given the cost, it is a no-brainer. Thank you very much Russ and Brian. I will now be spending Sunday afternoon drilling out the metal chassis I have for it... and I haven't had so much fun doing audio DIY in a long time.

[rjbaldwin]

I just noticed in a previous Post that someone mentioned the Metronome, or 'home made' version of which, added transparency? Not sure as I don't know what the Metronome does, some sort of re-clocker? Also not sure if it would be of much use in my USB-->I2S-->DAC (or indeed if it needs an extra Transformer / Power Supply.)

Russ, could you advise please, sorry being a bit dense, early Sunday Morning here... and if you feel it would be worthwhile in my setup I will purchase the necessary bits and test them out and report back here. You can tell I'm enjoying this... I hope...

[analog_sa]

Originally posted by rjbaldwin
Compared to top flght kit, the DAC perhaps lacks a little air or transparency and a touch of fluidity - at least in my system. This is only very slight and I am talking about a CD/DAC in the £5000 (GBP) bracket, even if it is an old one.

Let me guess: you enjoy a touch of exaggeration with your coffee on a Sunday morning

Originally posted by rjbaldwin
Also not sure if it would be of much use in my USB-->I2S-->DAC

Recently I went through the experience of adding an ASRC to my USB AD1852 . Difficult to say whether it adds to transparency but it certainly changes the sound in a dramatic way. I seem to like it but apparently there are a lot of detractors.

One thing it does not do is make your digital rig sound closer to a good turntable.

[rjbaldwin]

Thanks analog_sa, it was quite strong fresh coffee :-)

You have piqued my interest in ASRC ... but as I'm still not sure how the Metronome will fit into my current setup? If it's going to work I'd like to give it a try.

[analog_sa]

It will fit like a glove.

[maxlorenz]

Hi rjbaldwin,
I'm tasting my Sunday morning coffee here so I will participate

Compared to top flght kit, the DAC perhaps lacks a little air or transparency and a touch of fluidity - at least in my system. This is only very slight and I am talking about a CD/DAC in the �5000 (GBP) bracket, even if it is an old one.

I don't think it is necessarily an exaggeration...

Sunday morning has perhaps the best mains AC you can get
PC as source CAN be HiEnd, IMHO. Sorry I didn't get what OS do you play with.
Linux and MAC being best in that regard.
Did you know Soundcheck's thread about the multiplicity of improvements given by Linux?
Linux Audio the way to go!?

ASRC is good for SPDIF; I have a Monarchy Audio DIP upsampler feeding an M-audio superDAC and the benefits, again IMHO, are evident. With PC you can use software to change sample rate, I think, when reading Linux audio's thread and then the USB module reclocks it (?). Am I wrong? I'm running -ecdesigns- USB/DI2S module which reclocks BCK with a low jitter clock-shiftregister reclocker (NOS DAC) and this move brings lots of improvement in clarity, detail and fluidity. I can imagine it could be worthy also for OS DACs...

Apart that, no PS is so good that it could not become better...
And no output buffer is so good that it could not become better either I still can't play with discrete outputs but my experience has been that OS DACs tend to sound detailed but lacking bass and depth (probably a by-product of the former), a little sterile, and match well with warm sounding opamps like OPA627, which has better bass/midbass than LM4562 (and company) but lacks its transparency...

Enough of this audiophile relapse...

Good luck and enjoy!
M

PS: I have all the necessary now to make my "beta opus" work or see what went wrong. It is a thorn in the shoe for my self-esteem...

[Spartacus]

My ASRC is similar to the Metronome, but not the same. It fits between the receiver chip and the DAC chip. As far as we are concerned, it's benefit is that it allows us to use a low jitter local clock, and sonically it gives the usual effects of reduced jitter.

Dan